Template:Selected anniversaries/April 13

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  1923: Mathematician Karl Menger uses Gnomon algorithm techniques to fight crimes against mathematical constants.

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  1953: CIA director Allen Dulles authorizes the mind-control program Project MKUltra.

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  2008: Theoretical physicist John Archibald Wheeler dies. He linked the term "black hole" to objects with gravitational collapse, and coined the terms "quantum foam", "neutron moderator", "wormhole" and "it from bit".

https://en.wikipedia.org/wiki/John_Archibald_Wheeler

https://en.wikipedia.org/wiki/Robert_Watson-Watt

1960 – The United States launches Transit 1-B, the world's first satellite navigation system.